...Patients must have:- Non-small cell lung cancer (NSCLC) harboring activating EGFR mutations including tyrosine kinase inhibitor (TKI) sensitizing mutations (e.g., 19del and L858R), and/or approved TKI-resistance mutations (e.g., acquired TKI-resistance mutations, i.e., T790M, C797S, L792, L798I, exon 20 insertion), or any activating c-MET mutation/amplification (e.g., high-level c-MET amplification [MET/CEP7 > 5 or cfDNA ≥ 2 copies], or c-MET exon 14 skipping mutation).- Gastric/gastroesophageal junction (GC/GEJ) adenocarcinoma harboring an EGFR amplification (EGFR/CEP7 ≥2 or cfDNA ≥ 8 copies) or c-MET amplification (MET/CEP7 > 5 or cfDNA ≥ 2 copies).- Head and neck squamous cell cancer (HNSCC) or esophageal squamous cell cancer (ESCC).*NOTE: Patient identification will be based on previous treatment history with EGFR tyrosine kinase inhibitors and on local tests performed in CLIA-certified laboratories.• Cohort Expansion Part - Patients who have failed prior standard first-line treatment. ...